<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style type="text/css">
			div{
				width: 0px;
				height: 0px;
				border-top: 50px solid red;
				border-right: 50px solid yellow;
				border-bottom: 50px solid blue;
				border-left: 50px solid green;
				transform: rotate(45deg);
				border-radius:50px;
			}
		</style>
	</head>
	<body>
		<div></div>
	</body>
</html>
